One vertex per element, one color per generator, with an edge from x to x·s.
(5,6)(7,11)(8,10)(9,12)(13,14,16,18)(15,21,22,28)(17,25,24,20)(19,26,27,23)(2,3)(5,7)(6,9)(8,12)(10,11)(14,18)(15,22)(20,25)(23,26) involution — undirected(1,2,4,3)(13,15)(14,19)(16,22)(17,26)(18,27)(20,28)(21,25)(23,24)(6,10)(9,11)(14,18)(19,27)(20,25)(21,28) involution — undirected(1,3,4,2)(7,12)(9,11)(15,22)(19,27)(21,28)(23,26)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.